diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
@@ -14,6 +14,7 @@
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Lexer.h"
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/StringRef.h"
 
 #include "Plugins/ExpressionParser/Clang/ClangModulesDeclVendor.h"
@@ -141,6 +142,17 @@
   if (dm == nullptr)
     return;
 
+  // The macros directives below can potentially redefine builtin macros of the
+  // Clang instance which parses the user expression. The Clang diagnostics
+  // caused by this are not useful for the user as the source code here is
+  // generated by LLDB.
+  stream << "#pragma clang diagnostic push\n";
+  stream << "#pragma clang diagnostic ignored \"-Wmacro-redefined\"\n";
+  stream << "#pragma clang diagnostic ignored \"-Wbuiltin-macro-redefined\"\n";
+  auto pop_warning = llvm::make_scope_exit([&stream](){
+    stream << "#pragma clang diagnostic pop\n";
+  });
+
   for (size_t i = 0; i < dm->GetNumMacroEntries(); i++) {
     const DebugMacroEntry &entry = dm->GetMacroEntryAtIndex(i);
     uint32_t line;
diff --git a/lldb/test/API/commands/expression/macros/TestMacros.py b/lldb/test/API/commands/expression/macros/TestMacros.py
--- a/lldb/test/API/commands/expression/macros/TestMacros.py
+++ b/lldb/test/API/commands/expression/macros/TestMacros.py
@@ -129,3 +129,9 @@
         result = frame.EvaluateExpression("MACRO_2")
         self.assertTrue(result.GetError().Fail(),
                         "Printing MACRO_2 fails in the header file")
+
+        # Check that the macro definitions do not trigger bogus Clang
+        # diagnostics about macro redefinitions.
+        result = frame.EvaluateExpression("does_not_parse")
+        self.assertNotIn("macro redefined", str(result.GetError()))
+        self.assertNotIn("redefining builtin macro", str(result.GetError()))